117] FAUNA OF BIG VERMIUON RIVER— BAKER 19 



fauna of the Big Vermilion necessary. As a large mussel fauna lives in the 

 stream it follows as a corollary that there must also be a fish fauna of com- 

 parable size. Fortunately, Dr. S. A. Forbes, caused extensive collections 

 to be made in 1901, and these are listed on the maps accompanying the 

 work on the Fishes of Illinois, by Forbes and Richardson (1908). Fifty 

 species are recorded from the Big Vermilion River and its tributaries (see 

 Table II). It will be seen that at this date 28 species were found below 

 Urbana, in that portion of the stream now heavily polluted. 



Between the years 1908 and 1912, the Salt Fork between Urbana and 

 St. Joseph was deepened and straightened and the bottom fauna was com- 

 pletely destroyed. In the canal thus formed, for the purpose of carrying 

 ofiF the sewage of the Twin-Cities, no living clams, crayfish, or other clean 

 water animals have been found, and but one school of young fish (bull- 

 heads) was observed during several examinations of this part of the stream. 

 It is possible that during periods of high water in the spring, some hardy 

 fish may venture into this heavily polluted area. Below St. Joseph it is 

 quite probable that some fish are found during high water periods. A 

 few minnows were observed near the station called bench mark 655, about 

 fifteen miles below Urbana. A farm boy reported that bullheads could be 

 caught at high water on set lines. 



Below bench mark 655, and for some distance above it, fish must resort 

 in some numbers because of the presence of a fair sized mussel fauna (see 

 Table III). Young mussels, however, were not seen in any number above 

 the Homer Park dam, and it is possible that the upper stream is now little 

 visited by fish suitable for glochidial infection. Below the dam, young 

 mussels are plentiful at all points examined. 



Information concerning the species of fish that carry glochidia of the 

 river mussels is still of a fragmentary character. Suber (1912), Howard 

 (1914), and other workers of the U. S. Bureau of Fisheries haye published 

 considerable data on this subject, but much more is needed before one 

 can fully understand the relation between mussels and fish. 



Three species of mussels living in Salt Fork and other parts of the 

 Big Vermilion River are known to have glochidia encysted on five species 

 of fish, all of which have been reported from the Big Vermilion, viz.: 



Mussels Fish 



Lampsilis anodontoides Lepomis humilis 



" anodontoides Pomoxis spar aides 

 " anodontoides " annularis 



Quadrula metanevra Lepomis pallidus 



" pustulosa Pomoxis annularis 



" pustulosa Ictalurus punctatus 



